Fluid pressure producing device



March 24, 1942.

A. A. LOWEKE FLUID PRESSURE PRODUCING DEVICE.

Filed Aug. 12, 1940v INVENTOR. Bil/@Aeon Q LOWEKE ATTORNEY.

Patented Mar. 24, A1942 UNITED STAT-ES PATENT ()FFICE FLUID PRESSUREPBoDUcING DEVICE Aaron A. Lowke, Detroit, mich., assignmu vHydraulicBrake Company, Detroit, Mich., a

corporation of California Application August 12, 19'40, serial No.352,315

comms. (ci. en -54.6)

This invention lrelates to iluid pressure systems and more particularlyto uid pressure producing devices for such systems,

An object of the invention is to provide a two-phase fluid pressureproducing device operative to increase pressure on fluid without pro-Vportionately increasing the applied or activating force.

^ Another object of the invention is to'provide a uid pressure producingdevice including a low pressure producing means and a high pressureproducing means, and means for maintaining the low pressure means instatic position upon attaining a predetermined pressure.

Other objects and advantages of the invention will appearfrointhefollowing description taken in connection with the drawing forming apart of this specication and in which Fig. 1 is a schematic View of abraking system embodying the invention, and

Y f Fig. 2 is a vertical sectional view'of a fluid diameter as theopening 42 in the head 48 of the cylinder 38 and in axial alignmenttherewith. The plug 58 also has a plurality of spaced passages 54therethrough providing communica'- y tions between the reservoir and thecylinder, Yand a sealing cup 56 seated on thel plug for control of thepassages is held against displacement by a retainer 58 clamped betweenthe plug and the pressure producing device incorporated in the system..Y

Referring to the drawing for more specific details of the invention, I6represents a i'luid pressure producing device including a reservoir I2having in its bottom a drain opening i4 normally closed as by a plug I6.The reservoir has a removable top I8 provided with a lling opening 20normally closed as by a plug 22 having openings'24 therethrough forventing the reservoir to the atmosphere.

Arranged in the wall of the reservoir is an opening 26 having securedtherein a valve housing 28 opening into the reservoir as by an intakeport 30 controlled by a spring pressed ball valve 32 enclosed inthehousing and adapted to be opened by a plunger 34 extended through theintake port 30 into the reservoir.

The reservoir also has in its wall an -opening 36 arranged in oppositelydisposed relation to the opening 26 and adjacent the bottom'of thereservoir. A cylinder 38 supported in the opening 36 extends partlywithin the reservoir and partly outside o the reservoir and the outerend of the cylinder has a head 40 provided with a concentric opening 42.The cylinder also has adjacent its head a discharge port 44 controlledas by a one-way valve 46. Y f

The end -of the cylinder 38 opening into the reservoir has a smallportion of increased diameter providing an annularfshoulder 48, andaplug 50 secured in this portion of the cylannular shoulder 48.

A piston supported in the opening 42 in the head 40 of the cylinder 38and the opening 52 in the plug 58 for reciprocation in the cylinder hasan external diameter materially smaller than the inner diameter of thecylinder and provides in conjunction with one another an annular chamber62.

The piston 60 has a head 64 normally seated on the retainer 58`in spacedrelation to the plug 50 so as to provide a chamber 66'between the backof the head 64 of the piston and the plug 50. The head has a pluralityof spaced passages 68 therethrough providing communications between thechambers 62 and 66, and a sealing cup 10 seated on the head 64 controlsthe passages 68. Another sealing cup 12 embraces the' piston 60 andseats on the head 42 of the cylinder 38 to inhibit seepage of iluid fromthe chamber 62 tion to the open end of the chamber and a discharge port84 communicating with the annular chamber 62 by way of passage 86through the partition. The chamber 86 also communicates with thepassages 84 as by a port 88.

A ballvalve 9 controls the discharge port 84 and a spring pressed piston82 in the chamber has thereon a sealing cup 84 and a concentricextension engaging the ball valve-'88 so -as to lnormally retain thevalve in closed position.

A piston 96 reciprocable in the chamber 18 has a plurality of passages98 therethrough. A sealing cup |68 seated on the head of the pistoncontrols the passages 98, and a spring |82 inter' posed between the cupand the partition 16 serves to retain the cup against displacement andalso to return the piston 96 to its retracted position. A Y

A shaft |04 mounted transversely of reservoir 'in the walls thereof hasa part extended outside of' the reservoir. An actuator |06 secured onthe shaft engages the piston 96 and the thrust pin 34 to normally retainthe valve 32 open, and a crank |08 also secured on the shaft isconnected as by a rod to a foot pedal lever ||2 rockable on a stub shaft||4 and connected as by a retractile spring ||6 to a fixed support ||8.

A fluid pressure delivery line |20 connected to the discharge port 44has a branch |22 connected to the valve 28- and other branches connectedrespectively to fiuid pressure actuated motors |24 preferably arrangedin pairs, one pair for actuating brakes associated with the front wheelsof a vehicle and another pair for actuating brakes associated with therear wheels of the vehicle.

The brakes are of conventional type, each including a fixed support orbacking plate |26, a rotatable drum |28 associated therewith, a pair offriction elements or shoes |30 pivoted on the backing plate forcooperation withv the drum, a retractile spring |32 connecting theshoes, and a motor corresponding to the motors |24 mounted on thebacking plate land connected to the shoes for activating the shoes intoengagement l with the drum against the resistance of the retractilespring.

In a normal operation, upon depressing the foot pedal lever 2, force istransmitted therefrom through the rod ||0, the crank |08 to the shaft|04 resulting in rotation of the shaft carrying with it the actuator|06. 'I'his movement of the actuator releases the plunger 34, whereuponthe valve 32 is urged to its seat to close the port 30, andsimultaneously therewith the piston 96 isadvanced on its compressionstroke.

During the initial movement of the piston 96 on its compression stroke,thesealing cup |00 on the head of the piston 96 covers the port 82 andthereafter as the piston 96 advances the piston 60 is also advanced dueto pressure on the fluid trapped in the chamber 'I8 maintained by theload on the valve 88, and as the pistons 60 and 96 further advance fluidis drawn from the reservoir through the passages 54 into the chamber 66and the fluid in the chamber 62 is displaced therefrom through thedischarge port 44 past the valve 46and through the fluid pressuredelivery lines |20 and branches thereof into the fluid pressure actuatedmotors |24 causing energization of the motors with the resultantactuation of the friction elements |30 into engagement with the drums|28 to effectively retard rotation of the drums.

Upon attaining predetermined pressure on the uid in the chambers 10 and80, the valve 88 cracks. 'Ihis results in the piston 60 assuming astatic position due to the -iluid trapped in the chamber 66 back of thehead 64 of the piston 60, also in advance .of the piston 96', todisplace fluid from the chamber 16 through the discharge port 84 pastthe valve 88 and through the passages 86 into the annular chamber 62,thence through the discharge port 44 past the valves 46 and; through thepressure delivery lines |20 into the motors |24 causing furtherenergization of the motors and the resultant further actuation of thefriction elementsinto engagement with the drums.

Upon completion of a braking operation, the foot pedal lever ||2 isreleased and is returned to its retracted position 'under the influenceofthe retractile spring lli. This results in retract-` ing the. rod ||land movement of thevshaft |04 Cil through an angle causing retraction ofthe actuator |06. This movement of the actuator results in release ofthe piston 96 and cracking of the valve 32. Upon release of the piston96, the piston is returned to its retracted position under the inuenceof the spring |02 and simultaneously therewith the piston 60 is returnedto its retracted position under the influence of the spring 14. As thepiston 60 returns to its retracted position, fluid in the chamber 66 isdisplaced therefrom through the passages 68 in the head 64 past thesealing cup 10 into the annular chamber 62 completely filling thechamber. During this period fluid is returning from the fluid pressureactuated motors and the uid pressure delivery lines connecting themotors to the cylinder and the reservoir, and this surplus of fluidenters the reservoir by way of the valve 32.

While this invention has been described in connection with certainspecific embodiments, the principle involved is susceptible of numerousother applications that will'readily occur to persons skilled in theart. The invention is, therefore, to be limited only as indicated by thescope of the appended claims.

Having thus described the various features of the invention, what Iclaim as new and desire to secure by Letters Patent is:

1. A fluid pressure'producing device compusing a cylinder, a pistonmovable therein having a head dividing the cylinder into two chambers,one having a discharge port and the other adapted to draw fluid thereinduring movement of the piston, means controlling the fluid drawn intothe chamber the piston having a small chamber communicating with thechamber having the dis.. charge port, means for control of thecommunication, and means for subjecting the fluid in the small chamberto pressure.

2'. A iluid pressure producing device comprising a reservoir, a cylindersupplied therefrom, a piston movable in the cylinder having a chambertherein, a head on thepiston dividing the cylinder into a compressionchamber and a suction chamber, means providing a communication betweenthe piston chamber and the compression chamber, means for control of thecommunication, and a piston movable in the piston chamber, said suctionchamber communicating with the reservoir and means responsive to fluidpressure in the suction chamber controlling said communication.

3, A fluid pressure producing device comprising a cylinder, a pistonmovable therein having a head dividing the cylinder into two chambers,one `having a discharge port and the other adapted to draw fluid thereinduring movement of the piston including a one way fluid inlet by-passmeans and a one way outlet fluid by-pass means, the piston having aninteriorly disposed chamber communicating with'the chamber having thedis- /charge port, means for control of the communication, and means forsubjecting the fluid in the small chamber to pressure.

4. A fluid pressure producing device comprising a reservoir, a cylindersupplied therefrom, a piston movable-in the cylinder, a head on thepiston dividing the cylinder into a compression chamber and a suctionchamber, a discharge port for the compression chamber', meanscontrolling the suction chamber and providing communication with thereservoir and compression chamber, a chamber in the piston communicatingwith the reservoir and the compression chamber, a piston movable in thechamber, and means in the piston controlling the communication betweenits chamber and the compression chamber.

5. A uid pressure producing device comprisa reservoir, a, cylindersupplied therefrom, a piston reciprocable in the cylinder, a head on thepistondividing the cylinder into two chambers, one having a dischargeport and -the second chamber adapted to draw iluid from the reservoirduring forward movement of the piston, means permitting discharge ofiiuid from the second chamber into the chamber having the discharge porton reverse motion of the piston, a chamber in the piston communicatingwith the reservoir and chamber having the discharge port, and individualmeans controlling the communications. 6. A iluid pressure producingdevice comprising a reservoir, a cylinder supplied therefrom, a pistonmovable in the cylinder, a head on the piston dividing the cylinder intoa compression chamber and a suction chamber, a, discharge port for thecompression chamber, a portion of the cylinder enclosing the suctionchamber and providing a communication therethrough with the reservoir,passages through the head of the piston providing communication betweenthe suction and compression chambers, means controlling thecommunication between the suction chamber and reservoir, meanscontrolling the communication between the suction and compressionchambers, a chamber in the piston, a piston movable in the chamber, saidpiston chamber communicating with the reservoir and compression chamber,and individual means for controlling said communications.

AARON A. LOWEKE.

